Nitrates

Nitrate products have a direct action on vascular smooth muscle and cause it to relax. This effect is felt in both the circulation in arteries and veins. Arterial relaxation reduces the pressures the heart has to pump against (afterload), whereas venous relaxation helps in pooling of venous blood, thereby decreasing the amount of blood returned to the heart (preload). These effects work together to decrease myocardial oxygen use. In addition, nitrates increase the use of the other small blood vessels in the heart (collaterals) so that there is better oxygen supply to the inner layers of the heart muscle.

Calcium Channel Blockers

Calcium is an electrolyte that helps move electrical impulses through cardiac tissue. Calcium channel blockers are drugs that help slow down the flow of calcium ions across the cell membrane, thus reducing the amount of calcium available for electrical impulse movement. The drugs in this group are used for a variety of actions. Some calcium channel blockers act directly on vascular smooth muscle to dilate (open up) coronary arteries and arterioles, which relieves anginal pain because more oxygen can go to the cardiac tissue. Other calcium channel blockers are used to reduce the response of the cardiac conduction system to electrical impulses and treat cardiac dysrhythmias. They are also used along with other drugs to treat hypertension. (See the sections on anti­dysrhythmics and antihypertensives for additional information on calcium channel blockers and beta-adrenergic blockers.)

Peripheral Vasodilators

n Assessment

Learn as much as possible about the health history of the patient. Ask about heart disease, other health problems, the possibility of pregnancy, allergies, smoking, and whether the patient is taking other drugs that may cause interactions. Get a full description of the angina pain.

n Diagnosis

What other problems does this patient have that may interfere with treatment? For example, is the patient overweight? Does he or she smoke? What is the patient’s understanding of what is happening? What is the patient’s nutritional status and what dietary habits does the patient have? Is there any problem with the patient’s kidneys?

n Planning

Many times angina may be reduced or controlled if the patient makes lifestyle changes. This might include stopping smoking, limiting alcohol, limiting salt (sodium), increasing physical exercise, losing weight, eating a balanced diet rich in fruits and vegetables with lots of potassium and magnesium, avoiding dietary saturated fats, reducing stress, and treating other diseases such as hypertension and hyperlipidemia. Some patients who have the coronary arteries blocked may be candidates for surgery (coronary arterial bypass grafts or percutaneous transluminal coronary angioplasty) to reduce the symptoms. Medications are also an important part of treatment.

n Implementation

n Evaluation

The drug should be stopped if blurred vision or dry mouth occurs. If the patient says that some of the sustained-release medication is being passed in the stool, it is likely that food moves through the patient’s GI tract too fast to allow the drug to be absorbed. Such patients may need to switch to transdermal or sublingual medication.

Older adult patients may have postural hypotension with these drugs and need to be watched very carefully. They may need to have someone with them when they take the medication.

The patient must learn the uses and limits of the nitrate being taken, understand the schedule of when to take the drug, and be given information about when to call for help if chest pain does not go away after taking the drug. There are many important things to learn about giving this medication by its various routes. A person who has been using a nitrate for a long time should not stop taking the drug suddenly as this may cause more angina.

n Patient and Family Teaching

n Assessment

Learn everything possible about the patient’s health history, including any drug allergies, other drugs being taken that may cause drug interactions, and other medical problems, including factors such as hypoxia (reduced blood oxygen), acid-base imbalance, increased or decreased potassium, or drug toxicity. It is good practice to always take an apical heart rate with any patient that may have an arrhythmia by placing the stethoscope in the left chest cardiac area. Some irregular heart rates are very weak and are difficult to accurately feel with a radial pulse.

n Diagnosis

Does the patient have other health problems that will affect therapy? Does the patient drink lots of caffeine? Smoke? Exercise? Is the patient overweight?

n Planning

An ECG should be obtained before medications are started. This will determine the status of the heart before treatment so that changes can be seen if treatment is helpful.

n Implementation

Vital signs must be taken before giving any antidysrhythmic medication. The nurse often has the responsibility of monitoring any changes that might develop in blood pressure or pulse while initial thrapy is given. Hospitalized patients often continue their antidysrhythmic medications when they go home, so the nurse might take advantage of every opportunity to teach patients about these medications and be prepared to answer questions.

n Evaluation

If the patient’s heart is not being watched with a cardiac monitor, the results from ECGs must be closely followed to see any changes. Electrolyte levels and other laboratory data should also be obtained.

n Patient and Family Teaching

HMG-CoA Reductase Inhibitors or Statins

The HMG-CoA reductase inhibitors are the first choice drugs used to treat hyperlipidemia. They are the most costly drugs for treating hyperlipidemia, but patients also tolerate them best, and they are highly effective at lowering LDL levels. The ability of the six drugs in this class to lower LDL levels can be roughly ranked in the following order, with the most powerful drug first: rosuvastatin, atorvastatin, simvastatin, pravastatin, lovastatin, and fluvastatin. Adverse effects are similar for all six of these agents. A switch from one drug to another may be needed if adverse reactions occur. Liver function tests (LFTs) should be monitored in patients taking these products.

Fibric Acid Derivatives

Gemfibrozil and fenofibrate are the preferred drugs of this class because they are more effective and have fewer adverse effects compared with some other drugs. Both are highly effective at lowering triglycerides and increasing HDL levels, but have little effect on lowering LDL levels. Gemfibrozil and fenofibrate are well tolerated but can cause liver toxicity and cholelithiasis (gallstones).

Bile Acid Sequestrants

Niacin or Nicotinic Acid

Niacin is one of the most effective antihyperlipidemics at lowering triglyceride levels and increasing HDL levels and is similar to the bile acid sequestrants in its ability to lower LDL levels. The main limit to the use of niacin is its adverse effect of flushing (red color in the face and neck), although patients generally develop an ability to tolerate this problem with continued use. Flushing occurs shortly after the drug is taken and can be reduced by taking aspirin (30 minutes before) and increasing the niacin dosage very slowly over 3 to 4 weeks from 500 to 1000 mg three times daily. Niacin reduces glucose tolerance and may cause hyperuricemia (high uric acid levels), so it should be used with caution in patients with diabetes or gout. It remains the cheapest antihyperlipidemic and is probably underused in practice.

Selective Cholesterol Absorption Inhibitors

Ezetimibe is the first agent in this new category of drugs. This drug stays in the intestinal wall and acts on the intestinal epithelial cells to partially limit the absorption of cholesterol from food and from other sources in the body.

n Assessment

Learn as much as possible about the health history of the patient, including any allergies, other medications that are being taken that may lead to drug interactions, diet, other things the patient has done to try to reduce cholesterol levels, and the possibility of pregnancy.

n Diagnosis

Does this patient have other problems that will interfere with this therapy? Does the patient have a family history that causes anxiety about early death? Does the patient have problems with exercise, diet, or stress that make it more difficult to follow the treatment plan?

n Planning

Encourage weight reduction when necessary, because obesity increases the risk of cardiovascular damage. The patient must be taught about the long-term nature of this disease and the need for lifelong diet changes. The nurse’s ability to work with the patient, win confidence, be aware of reactions, and provide encouragement will be important in gaining compliance with diet, medication, and lifestyle changes that may save the patient’s life. Frequent return visits to the health care provider will be necessary, so the nurse may have many chances to offer support and reinforcement.

n Implementation

n Evaluation

n Patient and Family Teaching

Increasing the Strength of Myocardial Contraction

Slowing Heart Rate

The second action of the cardiotonic drugs is to slow the heartbeat. They do this by: (1) slowing down the rate at which the pacemaker in the SA node begins the electrical cycle; and (2) by slowing the rate at which that information is passed through the rest of the heart. (See the discussion of cardiac conduction in the “Antidysrhythmics” section of this chapter.)

n Assessment

n Diagnosis

What other problems does this patient have that interfere with therapy? Is the patient overweight? Anxious? Unwilling to accept having cardiac problems?

n Planning

Know about two different types of dosages for patients taking digoxin: 1) the initial digitalizing dose (or loading dose); and 2) maintenance (regular daily) doses. More frequent and higher digitalizing doses are given when a patient begins taking digoxin so that a specific level of medication can be reached in the blood. When the amount of drug in the patient’s blood reaches the desired level, smaller maintenance doses are given once a day to maintain the blood level. How fast the desired drug level is reached is based on the dosage, the diagnosis of the patient, and many other factors.

n Implementation

Before giving each dose of a cardiotonic drug, the apical pulse rate (using a stethoscope and listening to the chest) should be taken for 60 seconds. In an adult, if the apical pulse rate is less than 60, the medication should not be given until the nurse has discussed the low rate with the health care provider and the provider has decided whether it should be given. If there are any symptoms of digitalis toxicity or if the patient’s condition has worsened since the last time the medi­cation was given, the nurse notifies someone in authority if they believe that the dose should not be given, so that a decision might be made.

n Evaluation

A big risk for patients taking a cardioglycoside is the chance they will get too much drug and have digitalis toxicity. Changes from the first time the patient is seen should be written down in the patient record. Vital signs, including daily weights, are very important to record. Patients with other lung, GI, kidney, or central nervous system (CNS) problems, patients taking many other medications (especially diuretics and electrolytes), and confused patients who are not eating or drinking well are all at risk for digitalis toxicity.

The nurse is alert to any changes in the patient that may suggest the patient has developed digitalis toxicity. The earliest symptom of digitalis toxicity is often extreme fatigue. Almost 100% of patients also experience anorexia. Other signs include nausea and vomiting, difficulty with reading (which may appear as visual alterations such as green and yellow vision, double vision, blurred vision, or seeing spots or halos), headaches, dizziness, weakness, confusion, depression, increased nervousness, and diarrhea. Digitalis toxicity may cause life-threatening dysrhythmias, such as bradycardia, tachycardia, and irregular rhythms.

The health care provider will order blood tests to measure the serum blood digitalis level. The serum level of digoxin that is needed to help the patient (be therapeutic) is 0.5 to 2 ng/mL (nanograms per milliliter), and the toxic serum level is 2.5 ng/mL. Digoxin has a rapid onset and a short length of action.

Episodes of digitalis toxicity may be treated with digoxin immune Fab (Digibind), which has antigen-binding fragments that come from specific antidigoxin antibodies. This product may save lives, but it requires careful monitoring of the patient’s vital signs and potassium levels and special plans for slowly reducing the amount of drug that is given to avoid causing other life-threatening events.

n Patient and Family Teaching

Diuretics

The action of all diuretics is to increase fluid loss from the body. Diuretics have been the main drugs used in antihypertensive therapy for the past 40 years and they are the first-line drugs used in many patients who have mild to moderate hypertension. They are popular because they work quite well, are quite safe, are well tolerated, and are not very expensive. Diuretics may be classed into four related groups: thiazides (for example, chlorothiazide and hydrochlorothiazide), the thiazide-like sulfonamides (for example, metolazone, and indapamide), loop diuretics (for example, furosemide and bumetanide), and the potassium-sparing diuretics (for example, amiloride, triamterene, and spironolactone). The most-effective diuretics are those that work at the loop of Henle.

Adrenergic Inhibitors

Renin-Angiotensin—Converting Enzyme Inhibitors and Angiotensin II Receptor Antagonists

Vasodilators

Vasodilators reduce systolic and diastolic blood pressure by direct relaxation of arteriolar smooth muscle, thus lowering peripheral vascular resistance. The exact way these drugs work is not known, but they appear to block calcium from moving through the cell membrane.

Calcium Channel Blocking Agents

Calcium channel blocking agents selectively limit the passage of extracellular calcium ions through specific ion channels of the cell membrane in cardiac, vascular, and smooth muscle cells. This causes a lowered peripheral vascular resistance and a fall in systolic and diastolic blood pressure. These drugs are now commonly used to decrease blood pressure.

Stage I: Lifestyle Changes

Before starting drug therapy for patients with hypertension, a lot of effort should be made to help patients reduce their risk factors. Lifestyle changes to help patients lose weight; increase physical activity; and reduce fat, salt, and calories in the diet are helpful in lowering blood pressure. Behavior change to assist them to stop smoking and reduce alcohol intake is also important.

Stage II: Drug Therapy

The drug of choice in starting antihypertensive therapy is an oral thiazide—or thiazide-like sulfonamide drug—or an adrenergic beta blocker. Other drugs are added if needed, based on how the patient responds to the first drug. Most thiazides or beta blockers are effective when given once a day. The drug is started at a low dosage and increased as needed until the maximum dose is reached. In many cases, one of the drugs by itself will reduce the diastolic blood pressure to the desired level. Because these drugs commonly produce hypokalemia, a potassium supplement may also be required. Loop diuretics are used when hypertension is severe and the blood pressure must come down quickly. An antiadrenergic agent may be added to the treatment plan if the maximum doses of diuretics or beta blockers fail to lower the blood pressure to the desired level. These two categories of drugs work well together to bring down blood pressure and lower the chance of side effects, and they are better than using an antiadrenergic agent alone. There are a variety of antiadrenergic drugs, so the patient can try different combinations to find the ones that work best. The patient should move on to the next level of drug treatment only if a drug regimen fails to adequately control blood pressure. It should be noted that beta blockers seem to be less effective in black and much older adult patients. Captopril is another drug that seems to be less effective in black patients.

Other drugs that might be added to the therapeutic plan are vasodilators. Vasodilators are most effective when used with a beta-adrenergic blocking agent to control the rapid heartbeat that often results from lowering peripheral resistance.

n Assessment

Learn as much as possible about the health history of the patient. Although the cause for most high blood pressure is unknown, the health care provider will look for any disease that might also cause hypertension, such as Cushing disease, Addison disease, renal artery stenosis, coarctation of the aorta, or pheochromocytoma. The nurse will want to ask about whether the patient has other diseases, allergies, or medications that may affect antihypertensives and diuretics.

The number of drug side effects and problems that occur when hypertension is not treated effectively is high, and good record keeping is important in learning if the patient is getting well.

n Diagnosis

Does the patient understand that high blood pressure medication may need to be taken for the rest of his or her life? Does the patient understand that to reduce high blood pressure, lifestyle changes may be as important as medication? What factors does the patient have that will make therapy difficult?

n Planning

Because there is no cure for high blood pressure, a lot of patient teaching and education is needed to help the patient understand what is happening and cooperate with successful treatment. Although taking the medication is important, it is also important to work on other things in the patient’s life, such as removing risk factors and changing the diet.

n Implementation

Many patients with hypertension do not feel sick, so they have a hard time being compliant with the treatment regimen. High blood pressure is a “silent disease” because it has no symptoms. Because patients may only have symptoms as a result of side effects from their medication, they may not want to take drugs. It is important to teach patients about what is really happening to them to help them understand their disease.

The high cost of antihypertensive drugs and the desire of patients to have control over their therapy lead many of them to explore the use of herbal medications to lower blood pressure. The Complementary and Alternative Therapies box describes some of the more common herbal products patients may use. Little standardized research has been done to discover whether herbal products are safe or effective.

Patients taking diuretics should avoid caffeinated beverages as the diuretic effect of caffeine plus their medications may cause them to become dehydrated.

Encourage patients to lose weight, lower sodium intake, avoid stress and emotional pressures, develop regular and reasonable exercise routines, and have hobbies or activities that make them feel good about themselves (improve self-esteem). Remind them that taking their medications is only a small part of the total treatment plan.

When taking loop or thiazide diuretics, the patient should eat or drink more potassium-rich foods such as citrus fruits; bananas; potatoes; dark, leafy vegetables; and nuts. If the patient is taking a potassium-sparing diuretics, he or she should avoid excessive quantities of these foods.

n Evaluation

In addition to taking the patient’s blood pressure, a good eye examination can tell if the patient’s hypertension is well controlled. The blood vessels of the eye can be seen by looking through the pupil into the eye with an ophthalmoscope. By examining the fundus of the eye, it is possible to tell whether the blood pressure has been high, even if it is low when the patient is seen. Many parts of the body are damaged by high blood pressure: the heart, the lungs, the eyes, and the kidneys. Ask if the patient has any complaints that might suggest problems in any of these areas (end-organ damage). Ask about side effects the antihypertensive medication might be producing. Men should always be asked about their sexual functioning, because impotence is often caused by these medications, and they may not share this information unless asked. They may not even realize sexual problems may be related to their medication.

n Patient and Family Teaching

Drugs for Urinary Incontinence

Urinary incontinence is when patients wet themselves or leak urine, and this problem may have many causes. Medications used in treating this problem include some anticholinergics and antispasmodics, alpha-adrenergic agonists, estrogens, cholinergic agonists, and alpha-adrenergic antagonists. The anticholinergic agents stop contraction of the bladder and decrease the response of some of the bladder muscles. Antispasmodic drugs have a direct action on smooth muscle relaxation. Estrogen used either orally or vaginally may help restore urethral mucosa and increase vascularity, tone, and the ability of the urethral muscle to respond.

n Assessment

Learn the history of the urinary problem to make certain the patient’s symptoms are recorded correctly. The patient may be nervous about discussing these problems.

n Diagnosis

Find out the reason why the medication is being given. Are the symptoms because of another problem, or do they represent the major problem? (Is there other gynecologic or genitourinary disease present?) Read any medical records kept by the patient about urinary incontinence or voiding problems. This may be helpful in learning the cause of the symptoms.

n Planning

Teach the patient about what has caused the problem and how the medication will help.

n Implementation

Sometimes the patient is asked to keep a bladder diary. If so, explain clearly how to keep the records about wetting accidents and why. Give the patient a lot of support so they will be compliant.

n Evaluation

All of these medications should reduce symptoms. Explain to patients how they will know when the medication is working. For medications related to BPH, explain that treatment may be required for weeks or months before symptoms go away.